These have got to be the tiniest Philips heads screws imaginable. A triple zero bit works but god help you if the screw is in too tight. I've stripped one after managing to get the other out. I love Apple but their insistence on ridiculously tiny screws drives me crazy.

The two screws near each other and close to the edge of the iPad are really tiny. None of the screwdriver bits in iFixit's Precision screwdriver set are small enough to handle them. I'd assume a #0000 bit would do it.

Also, don't worry if the screw closest to the center of the iPad/furthest away from the two aforementioned screws doesn't quite line up with its hole. it should be easy enought to tuck it in later.